Housing and method for making the same

ABSTRACT

A housing is provided which includes an aluminum or aluminum alloy substrate, an aluminum layer and a corrosion resistant layer formed on the aluminum or aluminum alloy substrate in that order. The corrosion resistant layer is an Al—C—N layer. Then, La ions is implanted in the Al—C—N layer by ion implantation process. The atomic percentages of N and C in the Al—C—N gradient layer gradually increase from the side of Al—C—N gradient layer near the aluminum or aluminum alloy substrate to the other side of Al—C—N gradient layer, away from aluminum or aluminum alloy substrate. Therefore the housing has a high corrosion resistance. A method for making the housing is also provided.

This application is related to co-pending U.S. patent application Ser. Nos. 13/213,437, 13/191,602, entitled “HOUSING AND METHOD FOR MAKING THE SAME”. Such applications have the same assignee as the present application. The above-identified applications are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to a housing and a method for making the same.

2. Description of Related Art

Due to properties such as light weight and quick heat dissipation, aluminum and aluminum alloy are widely used in manufacturing components (such as housings) of electronic devices. Aluminum and aluminum alloy are usually anodized to form an oxide coating thereon to achieve a decorative and wear-resistant surface. However, the anodizing process is complicated and not very effective.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the exemplary process for surface treating aluminum or aluminum alloy and housings made of aluminum or aluminum alloy treated by the surface treatment. Moreover, in the drawings like reference numerals designate corresponding parts throughout the several views. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an embodiment.

FIG. 1 illustrates a cross-sectional view of an exemplary embodiment of a housing made of aluminum or aluminum alloy treated by present process.

FIG. 2 is a block diagram of an exemplary process for surface treating aluminum or aluminum alloy

FIG. 3 is a schematic view of a PVD machine used in the present process.

FIG. 4 is a schematic view of an ion implantation machine used in the present process.

DETAILED DESCRIPTION

FIG. 1 shows a device housing 10 according to an exemplary embodiment. The device housing 10 includes an aluminum or aluminum alloy substrate 11, aluminum layer 13 formed on the aluminum or aluminum alloy substrate 11, and a corrosion resistant layer 15 formed on the aluminum layer 13.

The aluminum or aluminum alloy substrate 11 may be produced by punching. The corrosion resistant layer 15 is an Al—C—N gradient layer doped with La ions implanted by the ion implantation process. The atomic percentages of N and C in the Al—C—N gradient layer gradually increase from the side of Al—C—N gradient layer near the aluminum or aluminum alloy substrate to the other side of Al—C—N gradient layer away from the aluminum or aluminum alloy substrate.

FIG. 3 shows a vacuum sputtering equipment 20, which includes a vacuum chamber 21 and a vacuum pump 30 connected to the vacuum chamber 21. The vacuum pump 30 is used for evacuating the vacuum chamber 21. The vacuum chamber 21 has a number of aluminum targets 23 and a rotary rack (not shown) positioned therein. The rotary rack drives the aluminum or aluminum alloy substrate 11 to rotate along a circular path 25, and the substrate 11 also rotates on its own axis while rotating along the circular path 25.

FIG. 2 shows an exemplary method for making the device housing 10, which may include:

The aluminum or aluminum alloy substrate 11 is pretreated. The pre-treating process may include:

The aluminum or aluminum alloy substrate 11 is cleaned with alcohol solution in an ultrasonic cleaner (not shown), to remove impurities such as grease or dirt from the aluminum or aluminum alloy substrate 11. Then, the substrate 11 is dried.

The aluminum or aluminum alloy substrate 11 is plasma cleaned. The aluminum or aluminum alloy substrate 11 is positioned in the rotary rack of the vacuum chamber 21. The vacuum chamber 21 is then evacuated to about 3.0×10⁻⁸ Pa. Argon gas (abbreviated as Ar gas having a purity of about 99.999%) is used as sputtering gas and fed into the vacuum chamber 21 at a flow rate of about 500 standard-state cubic centimeters per minute (sccm). The aluminum or aluminum alloy substrate 11 is applied with a negative bias voltage of about −100 volts (V) to about −180 V, then high-frequency voltage is produced in the vacuum chamber 21 and the Ar gas is ionized into plasma. The plasma strikes the surface of the aluminum or aluminum alloy substrate 11 to clean the surface of the aluminum or aluminum alloy substrate 11. The plasma cleaning of the aluminum or aluminum alloy substrate 11 lasts about 3 minutes (min) to about 10 min.

The aluminum layer 13 is vacuum sputtered on the pretreated an aluminum or aluminum substrate 11. In one exemplary embodiment, an aluminum layer 13 is then formed on the aluminum or aluminum alloy substrate 11 by physical vapor deposition (PVD). The formation of the aluminum layer 13 uses argon gas as the sputtering gas. The flux of the argon being from about 100 sccm to about 300 sccm. During sputtering, the power of the aluminum targets is of about 2 kw to about 8 kw, and the aluminum or aluminum substrate 11 is applied with a negative bias voltage of about −300 V to about −500 V. The vacuum sputtering of the aluminum layer takes about 5 min to about 10 min. The aluminum layer 13 has a thickness of about 100 nm to about 300 nm.

The corrosion resistant layer 15 is formed on the aluminum layer 13. The corrosion resistant layer 15 is an Al—C—N gradient layer formed by magnetron sputtering, and then the Al—C—N gradient layer is doped with La ions by the ion implantation process. An exemplary magnetron sputtering process for forming the corrosion resistant layer 15 includes: first, simultaneously applying argon, acetylene, and nitrogen, the flux of the argon being from about 100 sccm to about 300 sccm, the flux of the acetylene being from about 10 sccm to about 100 sccm and the flux of the nitrogen being from about 10 sccm to about 20 sccm; applying a bias voltage to the substrate of about −150 V to about −500V. During this process, the flux of the nitrogen and acetylene flow rates are both increased approximately about 10 sccm to about 20 sccm at a depositing interval of about every 10 minutes to about 15 minutes. The evaporation of the corrosion resistant layer 15 takes a total of about 30 min to about 90 min. The corrosion resistant layer 15 has a thickness of about 0.5 μm to about 2.0 μm.

The formation process of the corrosion resistant layer 15 forms a compact Al—C—N solid phase, thus increasing the density of the corrosion resistant layer 15. Therefore, corrosion resistance of the device housing 10 can be improved.

The atomic percentages of N and C in the Al—C—N gradient layer gradually increase alloy substrate to another side of Al—C—N gradient layer far away from the side of Al—C—N gradient layer near the aluminum or aluminum alloy substrate to the other side of Al—C—N gradient layer, away from the aluminum or aluminum alloy substrate. The gradient layer can decrease the mismatching of crystal lattices between the corrosion resistant layer 15 and aluminum layer 13. The formation of the aluminum layer 13 between the aluminum or aluminum alloy substrate 11 and the corrosion resistant layer 15 may improve the interface mismatch between the aluminum or aluminum alloy substrate 11 and the corrosion resistant layer 15, and can decrease residual stress in the corrosion resistant layer 15. Thus the device housing 10 becomes less prone to stress corrosion. The stress corrosion refers to the metal invalidity phenomenon under action of residual or applied stress and corrosive medium. The device housing 10 has a high corrosion resistance.

Lastly, the corrosion resistant layer 15 is implanted with La ion. The implanted ions can fill pores of the corrosion resistant layer 15 to increase the density of the corrosion resistant layer 15. Furthermore, the corrosion resistant layer 15 is a homogeneous amorphous film. Thus, the corrosion resistance of the aluminum or aluminum alloy substrate 11 can be improved.

La is implanted in the corrosion resistant layer 15 by ion implantation process. In an exemplary embodiment, the ion implantation process is performed by supplying a process gas into a processing chamber 20 of an ion implantation machine 100 as shown in FIG. 4. The machine 100 includes a plasma source 30 coupled to a RF source power 32. Plasma is generated by applying the RF source power 32 to dissociate ions from the process gas, thereby forming a source of ions that are accelerated toward and implanted into the substrate 11. The implanted ions react with the atoms and molecules of the surface layer of the substrate 11.

The ion implantation process may be performed under the following conditions. The processing chamber 20 is evacuated to maintain a pressure of about 1×10⁻⁴ Pa. The process gas supplied into the processing chamber 20 maintains a working atmosphere from about 0.1 Pa to about 0.5 Pa. The RF source power 32 may be controlled from about 30 kV to about 100 kV to form a beam of ions having an intensity of about 1 milliampere (mA) to about 5 mA. The density of the ions implanted in the ion implantation layer 13 may be from about 1×10¹⁶ ions per square centimeter (ions/cm²) to about 1×10¹⁸ ions/cm². The processing chamber 20 may be maintained at a normal room temperature. The La metallurgical bonds with the Al—C—N gradient layer by implantation, and forms the amorphous property. The structural characteristics of amorphous includes isotropic, no dislocation, and so on. Thus, the Al—C—N gradient layer is a homogeneous amorphous film, and the corrosion resistance of the substrate 11 can be improved.

EXAMPLES

Experimental examples of the present disclosure are described as following.

Example 1

The vacuum sputtering equipment 20 used in example 1 is a medium frequency magnetron sputtering equipment (model No. SM-1100H) manufactured by South Innovative Vacuum Technology Co., Ltd.

The substrate is made of aluminum.

Plasma cleaning: Ar gas is fed into the vacuum chamber 21 at a flow rate of about 280 sccm. The aluminum substrate 11 is applied with a negative bias voltage at −300 V. The plasma cleaning the aluminum substrate 11 takes about 9 min.

Sputtering of the aluminum layer 13: Ar gas is fed into the vacuum chamber 21 at a flow rate of about 300 sccm. The power of the aluminum targets 23 is 2 kw and the aluminum substrate 11 is applied with a negative bias voltage of −500 V. The depositing of the aluminum layer 13 takes 5 min.

Sputtering of the Al—C—N gradient layer: Argon, acetylene, and nitrogen are simultaneously applied. The flux of the argon is about 100 sccm, the flux of the acetylene is about 10 sccm, and the flux of the nitrogen is about 10 sccm. A bias voltage about −500 V is then applied to the substrate. Both the nitrogen and acetylene flow rates are each increased about 10 sccm about every 10 minutes and evaporate the aluminum target at a power of about 5 kw. The depositing of the Al—C—N gradient layer takes a total of 30 min.

Ion implanting La ions comprises: the processing chamber is evacuated to maintain a pressure of about 1×10⁻⁴ Pa, the process gas maintains a working atmosphere of about 0.1 Pa in the processing chamber. The RF source power is at about 30 kV to form an ion beam with an intensity of about 1 mA. The density of the ions implanted in the ion implantation layer is about 1×10¹⁶ ions/cm².

Example 2

The vacuum sputtering equipment 20 used in example 2 is the same in example 1

The substrate is made of 3003 type aluminum alloy.

Plasma cleaning: Ar gas is fed into the vacuum chamber 21 at a flow rate of about 280 sccm. The aluminum alloy substrate 11 is applied with a negative bias voltage at −300 V. The plasma cleaning the aluminum or aluminum alloy substrate 11 takes about 7 min.

Sputtering of the aluminum layer 13: Ar gas is fed into the vacuum chamber 21 at a flow rate of about 350 sccm. The power of the aluminum targets 23 is 2 kw and the aluminum alloy substrate 11 is applied with a negative bias voltage of −500 V. The depositing of the aluminum layer 13 takes 7 min.

Sputtering of the Al—C—N gradient layer: Argon, acetylene, and nitrogen are simultaneously applied, the flux of the argon is about 200 sccm, the flux of the acetylene is about 60 sccm and the flux of the nitrogen is about 15 sccm; A bias voltage −300 V is then applied to the substrate. Both the nitrogen and acetylene flow rates increase about 15 sccm about every 12 minutes and evaporate the aluminum target at a power of about 5 kw. The depositing of the Al—C—N gradient layer takes a total time of 60 min.

Ion implanting La ions comprises: The processing chamber is evacuated to maintain a pressure of about 1×10⁻⁴ Pa, the process gas maintains a working atmosphere of about 0.1 Pa in the processing chamber. The RF source power is at about 60 kV to form an ion beam with an intensity of about 2 mA. The density of the ions implanted in the ion implantation layer is about 1×10¹⁷ ions/cm².

Example 3

The vacuum sputtering equipment 20 used in example 3 is the same in example 1.

The substrate 11 is made of 5252 type aluminum alloy.

Plasma cleaning: Ar is fed into the vacuum chamber 21 at a flow rate of about 160 sccm. The aluminum alloy substrate 11 is applied with a negative bias voltage at −400 V. The plasma cleaning the aluminum alloy substrate 11 takes about 6 min

Sputtering of the aluminum layer 13: Ar gas is fed into the vacuum chamber 21 at a flow rate of about 300 sccm. The power of the aluminum targets 23 is 8 kw and the aluminum alloy substrate 11 is applied with a negative bias voltage of −300 V. The depositing of the aluminum layer 13 takes a total time of 10 min.

Sputtering of the Al—C—N gradient layer: simultaneously applying argon, acetylene, and nitrogen, the flux of the argon is about 300 sccm, the flux of the acetylene being is 100 sccm, and the flux of the nitrogen is about 20 sccm. A bias voltage about −150 V is then applied to the substrate; Both the nitrogen and acetylene flow rates increase about 20 sccm about every 15 minutes and evaporate the aluminum target at a power of about 5 kw. The depositing of the Al—C—N gradient layer takes a total time of about 90 min.

Ion implanting La ions comprises: The processing chamber is evacuated to maintain a pressure of about 1×10⁻⁴ Pa, and the process gas maintains a working atmosphere of about 0.1 Pa in the processing chamber. The RF source power is at about 100 kV to form an ion beam with an intensity of about 5 mA. The density of the ions implanted in the ion implantation layer is about 1×10¹⁸ ions/cm².

It is to be understood, however, that even through numerous characteristics and advantages of the exemplary disclosure have been set forth in the foregoing description, together with details of the system and function of the disclosure, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

What is claimed is:
 1. A housing, comprising: a substrate made of aluminum or aluminum alloy; an aluminum layer formed on the aluminum or aluminum alloy; a corrosion resistant layer formed on the aluminum layer; wherein the corrosion resistant layer is an Al—C—N gradient layer doped with La ions, the atomic percentages of N and C in the Al—C—N gradient layer gradually increase from the side of Al—C—N gradient layer near the aluminum or aluminum alloy substrate to the other side of Al—C—N gradient layer, away from aluminum or aluminum alloy substrate.
 2. The housing as claimed in claim 1, wherein the corrosion resistant layer has a thickness of about 0.5 μm-about 2.0 μm.
 3. The housing as claimed in claim 1, wherein the aluminum layer has a thickness of about 100 nm-about 300 nm.
 4. A method for surface treating aluminum or aluminum alloy, the method comprising: providing a substrate made of aluminum or aluminum alloy; forming an aluminum layer on the substrate by physical vapor deposition; forming a corrosion resistant layer formed on the aluminum layer, the corrosion resistant layer is an Al—C—N gradient layer doped with La ions which is implanted by ion implantation process, the atomic percentages of N and C in the Al—C—N gradient layer gradually increase from the side of Al—C—N gradient layer near the aluminum or aluminum alloy substrate to the other side of Al—C—N gradient layer, away from aluminum or aluminum alloy substrate.
 5. The method as claim in claim 4, wherein the step of forming Al—C—N gradient layer comprises: simultaneously applying argon, acetylene, and nitrogen, the flux of the argon being from about 100 sccm to about 300 sccm, the flux of the acetylene being from about 10 sccm to about 100 sccm and the flux of the nitrogen being from about 10 sccm to about 20 sccm; applying a bias voltage to the substrate of about −150 V to about −500 V; the flux of the nitrogen and acetylene flow rates are both increased approximately about 10 sccm to about 20 sccm at a depositing interval of about every 10 min to about 15 min. and evaporating the Al—C—N gradient layer taking a total time of about 30 min to about 90 min.
 6. The method as claim in claim 4, wherein, ion implanting La ions comprises: evacuating the processing chamber to maintain a pressure of about 1×10⁻⁴ Pa, the process gas maintains a working atmosphere from about 0.1 Pa to about 0.5 Pa in the processing chamber.
 7. The method as claim in claim 6, wherein the step of ion implanting La ions further comprises supplying a RF source power to dissociate the ions from the process gas.
 8. The method as claim in claim 6, wherein the RF source power is controlled from about 30 kV to about 100 kV to form a beam of the ions with an intensity from about 1 mA to about 5 mA.
 9. The method as claimed in claim 6, wherein the density of the ions implanted in the ion implantation layer is of about 1×10¹⁶ ions/cm² to about 1×10¹⁸ ions/cm².
 10. The method as claimed in claim 6, wherein the step of forming the aluminum layer comprises: using argon gas as sputtering gas, the flux of the argon being from about 100 sccm to about 300 sccm, the power of the aluminum targets is of about 2 kw to about 8 kw, the substrate is applied with a negative bias voltage is of about −300 V to about −500 V, vacuum sputtering the aluminum layer takes about 5 min to about 10 min.
 11. The method as claim in claim 4, wherein the method further comprises polishing and ultrasonically cleaning the aluminum or aluminum alloy substrate before forming the aluminum layer. 